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PremultiplyAlpha fix to avoid divide-by-zero

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This commit is contained in:
Chuck Walbourn 2020-02-13 23:08:54 -08:00
parent 53b8522394
commit 1c6f993963
1 changed files with 11 additions and 5 deletions
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16
DirectXTex/DirectXTexPMAlpha.cpp
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@ -124,7 +124,10 @@ namespace
{ {
XMVECTOR v = *ptr; XMVECTOR v = *ptr;
XMVECTOR alpha = XMVectorSplatW(*ptr); XMVECTOR alpha = XMVectorSplatW(*ptr);
alpha = XMVectorDivide(v, alpha); if (XMVectorGetX(alpha) > 0)
{
alpha = XMVectorDivide(v, alpha);
}
*(ptr++) = XMVectorSelect(v, alpha, g_XMSelect1110); *(ptr++) = XMVectorSelect(v, alpha, g_XMSelect1110);
} }
@ -143,9 +146,9 @@ namespace
assert(srcImage.width == destImage.width); assert(srcImage.width == destImage.width);
assert(srcImage.height == destImage.height); assert(srcImage.height == destImage.height);
static_assert(static_cast<int>(TEX_PMALPHA_SRGB_IN) == static_cast<int>(TEX_FILTER_SRGB_IN), "TEX_PMALHPA_SRGB* should match TEX_FILTER_SRGB*"); static_assert(static_cast<int>(TEX_PMALPHA_SRGB_IN) == static_cast<int>(TEX_FILTER_SRGB_IN), "TEX_PMALPHA_SRGB* should match TEX_FILTER_SRGB*");
static_assert(static_cast<int>(TEX_PMALPHA_SRGB_OUT) == static_cast<int>(TEX_FILTER_SRGB_OUT), "TEX_PMALHPA_SRGB* should match TEX_FILTER_SRGB*"); static_assert(static_cast<int>(TEX_PMALPHA_SRGB_OUT) == static_cast<int>(TEX_FILTER_SRGB_OUT), "TEX_PMALPHA_SRGB* should match TEX_FILTER_SRGB*");
static_assert(static_cast<int>(TEX_PMALPHA_SRGB) == static_cast<int>(TEX_FILTER_SRGB), "TEX_PMALHPA_SRGB* should match TEX_FILTER_SRGB*"); static_assert(static_cast<int>(TEX_PMALPHA_SRGB) == static_cast<int>(TEX_FILTER_SRGB), "TEX_PMALPHA_SRGB* should match TEX_FILTER_SRGB*");
flags &= TEX_PMALPHA_SRGB; flags &= TEX_PMALPHA_SRGB;
ScopedAlignedArrayXMVECTOR scanline(static_cast<XMVECTOR*>(_aligned_malloc((sizeof(XMVECTOR)*srcImage.width), 16))); ScopedAlignedArrayXMVECTOR scanline(static_cast<XMVECTOR*>(_aligned_malloc((sizeof(XMVECTOR)*srcImage.width), 16)));
@ -167,7 +170,10 @@ namespace
{ {
XMVECTOR v = *ptr; XMVECTOR v = *ptr;
XMVECTOR alpha = XMVectorSplatW(*ptr); XMVECTOR alpha = XMVectorSplatW(*ptr);
alpha = XMVectorDivide(v, alpha); if (XMVectorGetX(alpha) > 0)
{
alpha = XMVectorDivide(v, alpha);
}
*(ptr++) = XMVectorSelect(v, alpha, g_XMSelect1110); *(ptr++) = XMVectorSelect(v, alpha, g_XMSelect1110);
} }